Evaluating the impact of different afforestation timescales on the soil quality in a typical watershed valley using the criteria importance through intercriteria correlation method and gray target model

Soil quality evaluation is the foundation for understanding current situation of soil and promoting sustainable utilization land resources. However, impacts different long-term afforestation timescales on in a typical watershed valley area still insufficient. Here, based samples collected from years 2, 5, 11, 15, 31 natural sample plots with similar site conditions same region, gray target model criteria importance through intercriteria correlation (CRITIC) method are used this study to evaluate corresponding Tibet Plateau. Results show that: (1) The most positive physical chemical indexes increase analysis characteristics, variation, fertility grade 13 areas. content greater than that afforestation. (2) bullseye degree divided into five grades according principle equal division integration. plot after 15 4. other 5. (3) index (SQI) generally increases forestation years. indicate SQI (0.709) > (0.662) (0.426) 11 (0.348) 2 (0.309) 5 (4) full data set verifies effectiveness model. two methodologies consistent can verify each other’s accuracy. coefficient results reaches 0.957. This finds have improved valley. Available phosphorus, silt, water main factors impacting timescales.